AU619322B2

AU619322B2 - Smoking article

Info

Publication number: AU619322B2
Application number: AU38816/89A
Authority: AU
Inventors: Charles R. Hayward; John Robert Hearn; Kenneth S. Houghton; Harry V. Lanzillotti; A. Clifton Lilly Jr.; D. Bruce Losee Jr.; Edward B. Sanders; Mark A. Serrano
Original assignee: Philip Morris Products SA
Current assignee: PHILIP MORRIS PRODUCTS Inc
Priority date: 1988-07-22
Filing date: 1989-07-21
Publication date: 1992-01-23
Anticipated expiration: 2009-07-21
Also published as: HUT52355A; NO893003L; CN1019734B; PT91243B; JPH0284165A; MY104095A; KR910002388A; HK1007262A1; HU204686B; NZ230010A; EP0352109B1; IL91022A; JP3012253B2; PH26722A; DK362589A; DK362589D0; BG50145A3; EP0352109A2; NO893003D0; ATE132013T1

Abstract

A smoking article in which a flavored aerosol is generated by heat transfer to a flavor bed (21) from the combustion of a carbon heat source (20) is provided. The article generates substantially no sidestream smoke. The transfer of heat from the heat source to the flavor bed is accomplished by convective and radiative heat transfer.

Description

ti 1IvrejiLurb asignect tne invention to thie applicant.

Declared at Richmond,.VirgJi .ii .a .U.SA this... day op~~e18 8 Jo, an Hari, Vice President Li

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iii U~Euu Australia V~ 32 2 Form PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE Short Title: Int. CI: Application Number: C Lodged:

C

4: C C Complete Specification-Lodged: cd Accepted: Lapsed: Published: Priority: 1 Related Art:

C

tf Narme of Applicant: TO BE COMPLETED BY APPLICANT PHILIP MORRIS PRODUCTS INC.

Address of Applicant: Actual Inventor: Address for Service: 3601 Canrrerce Road, Richmond, Virginia of America 23234, United States MARK A. SERRANO, KENNETH S. HOUGHTON, EIYV'ARD B. SANDERS, A.

CLIFTON LILLY JIr., CHARLES R. HAYWRD, JOHN ROBE.-T HEARN, D.

BRUCE LOSEE Jr. anid HARRY VINCENT LANZILJ..(YTI CALLINANS Patent Attorneys, of 48-50 Bridge Road, Richmond, State of Victoria, Australia.

"SMOKING ARTICLE" Complete Specification for the invention entitled: The following statement is a full description of this invention, including the best method of performing it known to me:-* Note: The description is to be typed in doubld spacing, pica type face, in an area not exceeding 250 mm in depth and 160 mm in width, on tough white paper of good quality and it is to be inserted inside this form.

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-la- PM-1322 FOREIGN SMOKING ARTICLE Background of the Invention This invention relates to smoking articles which produce substantially no visible sidestream 5 smoke. More particularly, this invention relates to

CC,

a smoking article in which the sensations associated with the smoking of tobacco are achieved without the

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C burning of tobacco.

t C A substantial number of previous attempts C' 10 have been made to produce a smoking article which produces an aerosol or vapor for inhalation, rather than conventional tobacco smoke. For example, according to one previous attempt, a smoking article is made of a charcoal rod and a separate carrier 15 -impregnated with flavorants and a synthetic "smoke" C cc forming agent which is heated by the burning charcoal SccC -od. The charcoal rod is coated with a concentrated sugar solution so as to form an impervious layer during burning. It was thought that this layer would J 20 contain the gases formed during smoking and concen- S trate the heat thus formed.

C cc Another smoking article employs burning tobacco in the form of a conventional cigarette to heat a metallic cylinder containing a source of nicotine, such as reconstituted tobacco or tobacco extract. During smoking, the vapors released from the material inside the metal tube mix with air I s~ r~ -2inhaled through an open end of the tube which runs to the burning end of the smoking article. Ellis et al.

U.S. Patent 3,356,094 shows a similar smoking article in which the tube becomes frangible upon heating, so that it would break off and not protrude when the surrounding tobacco had burned away.

A third smoking article produces a nicotinecontaining aerosol by heating, but not burning, a flavor generator. The flavor generator could be fabricated from a substrate material such as almumina, natural clays and the like, or tobacco filler. The flavor generator is impregnated with thermally.

releasable flavorants, including nicotine, glycerol, menthol and the like. Heating of the flavor generator 0 00 ooo0 15 is provided by hot gases formed as a result of the o...o0 combustion of a fuel rod of pyrolized tobacco or 0 0 0 o other carbonaceous material.

0 00 0o A fourth smoking article is a variation of 0 0 0 o* the third smoking article, but employing a short 00 00 0 0 20 fuel element. The performance of the article is said to be improved by maximizing heat transfer between the fuel element and the aerosol generator.

00 This is effected by preventing heat loss by insula- 00 0 tion, and by enhancing heat transfer between the 0 00 o.

0 0 25 burning fuel and the flavor generator by a metallic 0 conductor. A spun glass fiber insulator surrounds 0 the fuel element and aerosol generator assembly.

The fourth smoking article suffers from a number of drawbacks. First, the resilient glass °S°0o 30 fiber insulating jacket is difficult to handle on 00 0 0o °t modern mass production machinery. Second, the glass fibers may become dislodged during shipping and migrate through the pack to rest on the mouth end of the article, giving rise to the potential for the inhalation of glass fibers into the smoker's mouth.

Additionally, the use of a metallic heat conductor may be somewhat inefficient because the conductor -3itself absorbs much of the heat produced by the fuel element.

Sumr of the Invention In accordance with this invention, there is provided a smoking article having a mouth end and a distal end remote from said mouth end, said smoking article comprising: an active element at said distal end in fluid communication with said mouth end, said active element comprising: a substantially non-combustible substantially cylindrical hollow sleeve having internal and external walls, and having a first end at said distal end and 4 10 a second end opposite said first end, I a heat source contained in said sleeve adjacent Said first end, said heat C f source having a fluid passage therethrough, and a flavor bed in said sleeve adjacent said second end thereof; said 0*8 ~smoking article characterized in that: *said flavor bed is in radiative and conv'ective heat transfer relationship with said heat source; and I said sleeve is ak-Fermeable adjacent said heat source for admitting air Sto support combustion of said heat source, and is air-impermeable adjacent said C 'C flavor bed to prevent combustion of material in said flavor bed; whereby: when said heat source is ignited and air is drawn through said smoking 4 article, air is heated at it is drawn through said fluid passage, said heated air flowing through said flavor bed, releasing a flavored aerosol, and carrying it to said mouth end.

Brief Description of the Drawings The advantages of the invention will be appare~nt upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which: Fig. 1 is an exploded perspective view of a first preferred embodiment of a smoking article 9,ocording to the pre2sent invention; Fig. 2 is a longitudinal cross-sectional view of the smoking article of Fig.

-4- 1, taken from line 2-2 of Fig. 1; Fig. 3 is an end view of the smoking article of Figs. 1 and 2, taken from line 3-3 of Fig. 2; L £q 4 4£6 FIG. 4 is a radial cross-sectional view of the smoking article of FIGS. 1-3, taken from line 4-4 of FIG. 2; FIG. 5 is a radial cross-sectional view of the smoking article of FIGS. 1-4, taken from line of FIG. 2; FIG. 6 is a radial cross-sectional view of the smoking article of FIGS. 1-5, taken from line 6-6 of FIG. 2; FIG. 7 is an exploded perspective view of the active element of the smoking article of FIGS. 1-6; FIG. 8 is a longitudinal cross-sectional view of the active element of the smoking article o; o" 15 of FIGS. 1-7 taken from line 8-8 of FIG. 7; FIG. 9 is a diagram of testing apparatus o 0 00,00 for measuring permeability of smoking articles oo a* according to the invention; o 0 FIG. 10 is a longitudinal cross-sectional 00 o 0 0 20 view of a second preferred embodiment of a smoking article according to the invention; FIG. 11 is a radial cross-sectional view of the smoking article of FIG. 10, taking from line o0o o 11-11 of FIG. 0 f.0 °oo 25 FIG. 12 is an exploded perspective view .)f the active element of the smoking article of FIGS.

10-11; and FIG. 13 is a longitudinal cross-sectional view of the active element of the smoking article of o0 30 FIGS. 10-12, taken from line 13-13 of FIG. 12.

0 0 0 0 Detailed Description of the Invention A first preferred embodiment of a smoking article according to the present invention is shown in FIGS. 1-8. Smoking article 10 consists of an active element 11 and an expansion chamber tube 12, -6overwrapped by cigarette wrapping paper 14, and a filter element 13 attached by tipping paper 205.

Wrapping paper 14 preferably is a cigarette paper treated to minimize thermal degradation, such as a magnesium oxide, or other suitable refractory type, cigarette paper. As discussed in more detail below, active element 11 includes a carbon heat source and a flavor bed 21 which releases flavored vapors and gases when contacted by hot gases flowing through the heat source. The vapors pass into expansion chamber tube 12, forming an aerosol which passes to mouthpiece element 13, and thence into the mouth of a smoker.

Carbon heat source 20 preferably is subn 15 stantially pure carbon, preferably with some catalysts or burn additives. Carbon heat source 0 0opreferably is formed from charcoal and has one or more longitudinal passageways therethrough. These 0o° longitudinal passageways preferably are in the shape S 20 of multi-pointed stars having long narrow points and a small inside circumference. Carbon heat source has a void volume greater than about 50% with a pore size between the charcoal particles of about one to o. about 2 microns. Carbon heat source 20 has a weight o 0 0o 25 of about 81 mg/10 mm and a density between about 0.2 g/cc and about 1.5 g/cc. The BET surface area eo. of the charcoal particles used in carbon heat source 20 is in the range of about 50 m 2 /g to about 2000 m 2 /g.

Flavor bed 21 can include any material 0 o that releases desirable flavors and other compounds when contacted by hot gases. In a smoking article, the flavors and other compounds may be those associated with tobacco, as well as other desirable flavors.

Thus, suitable materials for flavor bed 21 may include tobacco filler or an inert substrate on which desirable compounds have been deposited. In a preferred -7- 0 0 0 00 0008 0 00 00 0 0 00 0 00 00 0 0 0 00 0 embodiment, flavor bed 21 is a packed bed of pelletized tobacco. The pellets are preferably formed by combining in an extruder particularized tobacco iaterials having a size of from about 20 mesh to about 400 mesh, preferably about 150 mesh, an aerosol precursor, for example, glycerine, 1,3-butanediol or propylene glycol, that can be widely dispersed among the tobacco particles, and a finely divided filler material, for example, calcium carbonate or alumina, to increase the thermal load to prevent the hot cases from raising the temperature of the pellets above their thermal decomposition temperature. The materials are mixed to form a mixture, and the mixture is extruded out a die 15 typically having a plurality of orifices into spaghetti-like strands of about the same diameter. The extruded strands are cut into lengths, preferably of uniform length. Tihe pellets preferably are uniformly dimensioned and comprise a mixture of about 15% to 20 about 95% tobacco material, about 5% to about aerosol precursor, ana about 0% to about 50% filler material.

Given sufficient ox ygen, as discussed in more detail below, heat source 20 will burn 'to produce 25 -mostly carbon dioxide. As also discussed below, radiant energy reflector sleeve 22 of active element 11 is substantially non-combustible, and does not burn during smoking of article 10. Further, article 10 is constructed in such a way that the gases flowing 30 through flavor bed 21 have a reduced oxygen content, also discussed below, so that the constituents of flavor bed 21 undergo pyrolysis and not combustion even if their temperature is high enough to ignite them otherwise. There is substantially no visible sidestream smoke when article 10 is smoked.

Turning to the details of the construction of article 10, active element 11 is housed in a com- 0000 0 0 9 00 8 0 00 00 8 0 88 08 00 0 448 4 000084 0 8 00 8 0 00 0 08 posite sleeve including radiant energy reflector sleeve 22 and, preferably, an inner sleeve 23 within radiant energy reflector sleeve 22. (As used herein, unless otherwise indicated, the word "sleeve" refers to the composite sleeve.) Inner sleeve 23 is folded to provide a lip 24 which holds carbon heat source suspended away from the interior wall of radiant energy reflector sleeve 22, leaving an annular space 25. Flavor bed 21 is held within inner sleeve 23 between lip 24 and heat source 20 on one end, and a screen-like clip 26, which holds in the pellets of V bed 21 while allowing the aerosol to pass through into expansion chamber tube 12, on the other end.

Expansion chamber tube 12 gives article 10 the length, and thus the appearance, of an ordinary cigarette.

,,The mouth end portion 120 of inner sleeve 23 extends beyond the mouth end of radiant energy reflector sleeve 22 and fif~z into expansion chamber tube 12.

Wrapper 14 holds active element 11 and expansion chamber tube 12 together. Preferably, cigarette wrapping paper 14 will have sufficient porosity to allow air to be *admitted through paper 14 and radiant energy reflector sleeve 22 to support combustion of heat source 20. Alternatively, paper 14 may be perforated, such as by laser perforation, in the region of radiant energy reflector sleeve 22 which surrounds heat source Preferably, aluminum insert 27, fitted into inner sleeve 23 behind clip 26, closes off the mouth end of active element 11, leaving only an I ~f0orifice 28 for the passage of the hot vapors.

Passage through orifice 28 causes the hot vapors to increase their velocity and then expand into expansion chamber tube 12. Expansion of the vapors and gases into the expansion chamber causes cooling of the saturated vapors to form a stable aerosol, thereby minimizing condensation on either of mouth- -9piece segments 29, 200, increasing the delivery of aerosol to the smoker. The degree of expansion, and therefore of cooling, may be controlled by varying the size of orifice 28 and the volume of expansion chamber 12.

Mouthpiece element 13 may be a hollow tube or may include a filter segment 29. Mouthpiece element 13 preferably includes two mouthpiece seg- I ments 29, 200. Mouthpiece segme-nt 29 ie a cellulose acetate filter plug 201 wrapped in plug wrap 202.

Segment 200 is a rod of tobacco filler, wrapped in plug wrap 203, which, in addition to further cooling the aerosol and providing some filtration, may impart additional tobacco taste. The tobacco filler in 0o 15 segment 200 is preferably cut at the vtandard 30 cuts Oao 0 per inch, but may be coarser to minimize filtration.

For example, the tobacco filler may be cut at about o 15 cuts per inch. The two segments 29, 200 of mouthad piece element 13 a.'e jointly overwrapped by plug wrap 204, and the entire mouthpiece element 13 is attached to the remaiader of article 10 by tipping 205.

Returning to the structure of active element 11, annular space 25 is provided so that the re is a 25 sufficient air flow to heat source 20 to allow for sustained combustion and so that conduction of heat to the outside is minimized. For the former reason, radiant energy reflector sleeve 22 is perforated and preferably has at least about 9.5% open area and a 4 L 30 permeability of about 9.1 to about 15.1, measured as 8 4 follows: A permeability test apparatus 90 as shown in FIG. 9 is assembled from tubing sections 91, 92, 93, 94 all having the same diameter as radiant energy reflector sleeve 22, which is integrated into apparatus 90. Nitrogen gas is pumped into opening o ai a 0 o o a 00 0 0 0a 0 00os 0 0 00 0 0 0O 00 0

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at a rate of 2 liters per minute. Opening 96 is open to the atmosphere. Gas is pumped out of opening 97 at a rate of 1 liter per minute. Because resistance to the flow of air through the wall of sleeve 22 is less than that through the tubing of apparatus air will be drawn in through the wall of radiant energy reflector sleeve 22 and out through opening 9" along with a quantity of nitrogen gas. A mass spectrometer probe 98 is positioned at the end of tube section 93 below tube section 94, and is connected by cable 99 to mass spectrometer 900. Cable 99 passes out of tube 94 at 901. The opening through which cable 99 passes is sealed so that no oxygen enters apparatus 90 except through the wall of radiant 15 energy reflector sleeve 22. The permeability of radiant energy reflector sleeve 22 is defined as the number of milliliters of oxygen per minute per square centimeter of surface area of the outer wall of radiant energy reflector sleeve 22 detected by probe 98 as 20 determined by mass spectrometer 900.

The permeability of radiant energy reflector sleeve 22 determines the mass burn rate of heat source It is desirable for article 10 to provide about 10 puffs under FTC conditions (a two-second, thirtyfive milliliter puff taken once a minute). If the mass burn rate of heat source 20 is too high, each puff taken by a smoker will deliver added flavor because the gases reaching flavor bed 21 will be hotter. However, because more of heat source 20 is 30 consumed in each puff, heat source 20 may be consumed in fewer than 10 puffs. Similarly, if the mass burn rate is too low, more than 10 puffs will be available, but each will deliver less flavor because the gases will be cooler. In addition, if the mass burn rate is too low, heat source 20 may extinguish before the smoker is ready to take another puff. A preferable mass burn rate has been found to be between about 00 0 0 o a 0 D 000 0 0 0 0 0 00 0 00 -11o0 0 o0 000 00000a 0 0 0 40a 00 0 4 9 mg/mmn and about 11 mg/min. To achieve r~.a range of mass burn rates, a permeability of between about 9.1 and about 15.1, measured in accordance with the method described, is preferred.

The air flow in element 11 into flavor bed 21 is through passage 206 in heat source 20. It is desirable that as large as possible a surface area of heat source 20 be in contact with the air flow to maximize the convective heat transfer to flavor bed 21, and also so tbat combustion is as complete as possible. For that same reason, passage 206 is not a simple cylindrical passage. i~kther, it has a many-sided cross section, such as the eightpointed star shown in the FIGURES. In fact, the 15 surface area of passage 206 in the preferred embodiment is greater than the surface area of the outer surface of heat source In order to minimize radiative heat loss from article 10, all inner surfaces of active element 11 are reflectorized. For example, radiant energy reflector sleeve 22 can be made from metallized paper.

More preferably, as seen in FIGS. 7 and 8, radiant energy reflector sleeve 22 is made up of a paper layer 70 and an inner foil layer 71. Foil layer 71 reflects heat radiated by heat source 20 back into heat source 20 to keep it hot and thus to ensure that it does not cool below its ignition temperature and become extinguished. The reflection of heat back into active element 11 also means that more heat is available for transfer to flavor bed 21.

Paper layer 70 may be made by spiral winding a paper strip or using other well-known techniques of paper tube-making. Preferably, however, paper layer 70 and foil layer 71 are passed together through a garniture, similar to that used in the making of conventional cigarettes, which forms them into a tube. In that preferred embodiment, the edges said flavor bed is in radiative and convective heat transfer relationship with said heat source; and ./2 -12of paper layer 70 overlap and are glued to one another.

Paper layer 70 is either porous or perforated, so that the required permeability, referred to above, can be achieved. Foil layer 71 is preferably made by taking a standard 0.0015-inch aluminum foil, embossing it to provide raised holes, and then calendering it to flatten the holes so that tha pe~rforated foil is more nearly smooth. Although calendering closes up the holes somewhat, the desired permeabi:lity is achieved as long as the embossed aluminwn sheet has at least 4% open area, preferably about 9.5% open area.

Although foil layer 71 reflects a substantial portion of the heat produced by heat source 0 *9 15 some of the heat may escape to the outside. For that reason, the paper used in paper layer 70 prefer- 000 0ably is modified to prevent combustion so that it o does not ignite when article 10 is smoked.

0 Inner sleeve 23 is also reflective, made of an outer aluminum layer 80, an inner aluminum layer 81, and an intermediate paper layer 82. Inner sleeve 23 may be made by taking two identical paper/ foil laminate strips and spiral winding them, paper :00 25 side to paper side, so that the two paper sides together form intermediate layer 82. The paper layers are preferably hard-calendered paper. In the a preferred embodiment, intermediate layer .32 also includes up to three layers of a paper trri ated to reduce thermal degradation, such as magnesium oxide, o~o~j 30 or other suitable refractory type, cigarette paper, 0 wound between the paper/foil laminate strips. Inner sleeve 23 is not made air permeable because flavor bed 21 is to be kept oxygen-deprived, so that no ignition of tobacco can take place which might introduce off tastes and thermal decompo'sition constituents to the aerosol. The foil layers 80, 81 keep air out, as well as reflecting radiant heat back in -13for maximum flavor generation. Of course, air could be kept out of flavor bed 21 in other ways, such as overwrapping radiant energy reflector sleeve 22 with an air-impermeable material (not shown) in the region of flavor bed 21. Foil layers 80, 81 should be as thin as possible so that they have low heat capacity, making more heat available to flavor bed 21. I Inner sleeve 23 is folded cver to make lip 24, which must be wide enough so that heat source can be held securely in place.

Finally, active element 11 is provided with a reflective end cap 15 which clips over radiant energy reflector sleeve 22 but is covered by wrapper 14.

Cap 15 has one or more openings 16 which allow air S°°o 15 into active element 11. Openings 16 preferably are located at the periphery of cap 15. In the preferred embodiment, there are six equiangularly spaced openings 0 00 each having a diameter of 0.080 in. Cap 15 increases Soo the reflection of radiation back into active element 11, 20 and also keeps heat source 20 from falling out of article 10 if it somehow becomes loose. This is important when it is considered that heat source smolders at a high temperature between puffs, and is 0 even hotter during puffs. Cap 15 also keeps in any 0oo 0 25 'ash that may form during burning of heat source It is preferred that article 10 have an oo 0 °oo outer diameter of 7.9 mm, similar to a conventional cigarette. Carbon heat source 20 preferably has a diameter of 4.6 mm and a length of 10.1 mm, while 30 active element 11 preferably has an overall length 00 o" of 26 mm. Mouthpiece element 13 preferably has a length of 21 mm, divided between a 10 mm cellulose acetate filter portion 29 and an 11 mm tobacco rod portion 200. Expansion chamber tube 12 preferably is 33 mm long, so that article 10 overall is 79 mm long, which is comparable to a conventional "long-

I

Complete Specification for the inventiori entitled: The following statement is a full description of this inventiont, including the best method of performing it known.

to me:- Note: The description is to be typed in double spacing, pica type face, in an area not exceeding 250 mm in depth and 160 mm in width, on tough white paper of good quality and it is to be inserted inside this form.

-14size" cigarette. In the preferred embodiments, lip 24 is 2.6 mm. wide.

A secoind, more particularly preferred embodiment of a smoking article according to the present invention is shown in FIGS. 10-13, any views of the second embod, which are not shown in FIGS.

the first preferred embodiment.

In the emnbodiment 100 of FIGS. 10-13, a spacer 101 within active element 110 holds the pellets of flavor bed 21 in spaced-apart relation from the end of carbon heat source 20. It. has been found that, as compared to the embodiment of FIGS. 1-8, the inclusion of spacer 101 provides more even o 00 0,0 00 15 tieating of the end of the flavor bed adjacent heat 009000source 20, because the jet of hot gases drawn through ~::passage 206 has time to spread out b,7fore reaching 0 00 flavor bed 21, so that it heats more of the end of 0 00 flavor bed 21. Similarly, inclusion of spacer 101 a00 000 20 prevents flashing of flavor bed 21 on lighting of smoking article 100. In the absence of spacer 101, flame drawn through passage 206 during lighting could 00 cause flavor bed 21 to ignite, or flash, but with 000 spacer 101 in place, any such flame spreads out over 000 25 spacer 101. Spacer 101 preferably is a metallic aluminum disk, which preferably is blackened 0a 4tc so that it will absorb heat from carbon heat source and radiate it to flavor bed 21.

The inclusion of spacer 101 provides other 4~ 0 30 advantages, as well. For example, it prevents small 00 particles from flavor bed 21, such as broken pieces of obacopellets, from falling through passage 206,andobstructing the front end of smoking article100betwean end cap 15 and heat source 20, or falling out of article 100 altogether if end cap is not provided. In addition, spacer 101 permits different degrees of packing of the same amount of the material inside the metal tube mix with air L* -I A -ispellets in flavor bed 21, by moving spacer 101 closer to or further from clip 26. Different degrees of packing of flavor bed 21 give rise to different degrees of resistance-to-draw of article 100, as well as different flavor characteristics. Finally, spacer 101, which holds the pellets of flavor bed 21 away from heat source 20, also prevents migration of flavor compounds from the pellets to heat source 20, where they might undergo pyrolysis and give rise to off tastes or thermal decomposition products.

Thus it is seen that a smoking article in which a flavored aerosol releasing material is efficiently heated by a carbonaceous heat source, which avoids the potential for inhalation of glass fibers by the smoker, which minimizes heat loss to the walls of the flavor bed, and which has both the look and feel of a conventional cigarette, is provided.

0 a 0 o 00 0 00 00 0 o o oso 0 00 00 0 0 6 C o0 a S00 a oo 0 I

Claims

1. A smoking article having a mouth end and a distal end remote from said mouth end, said smoking article comprising: an active element at said distal end in fluid communication with said mouth end, said active element comprising: a substantially non-combustible sub- stantially cylindrical hollow sleeve having internal and external walls, and having a first end at said distal end and a second endclcr to a-'th end, a heat source contained in said sleeve adjacent said first end, said heat source having a fluid passage therethrough, and 15 a flavor bed in said sleeve adjacent said second end thereof; said smoking article charac- terized in that: said flavor bed is in radiative and Sconvective heat transfer relationship with said heat source; and said sleeve is air-permeable adjacent said heat source for admitting air to support combus- end, tion of said heat source, and is air-impermeable adjacent said flavor bed to prevent combustion of material in said flavor bed; whereby: when said heat source is ignited and air is drawn through said smoking article, air is heated as it rough said fluid said Sheated air flowing through said flavor bed, releasing 30 a flavored aerosol, and carrying it to said mouth end.

2. The smoking article of claim 1 charac- terized in that said heat source is suspended in said sleeve spaced from said interior wall of said said sleeve spaced from said interior wall f said r L~i -17- sleeve, defining an annular space around said heat source.

3. The smoking article of claim 2 charac- terized in that said substantially non-combustible sleeve is of metallic foil and paper.

4. The smoking article of claim 3 charac- terized in that said metallic foil is aluminum foil. The smoking article of claim 3 charac- terized in that said substantially non-combustible sleeve is of a rolled paper/foil laminate.

S,

6. The smoking article of claim 3 charac- terized in that said paper is porous and said foil 0 a is perforated. a'

7. The smoking article of claim 3 charac- S 4 terized in that said paper is non-porous and said paper and said foil are perforated.

8. The smoking article of claim 3 charac- terized in that said interior wall of said sleeve is .C "of said metallic foil, said foil reflecting heat produced by said heat source back toward said heat ir 5 source, to aid in maintaining combustion thereof.

9. The smoking article of claim 2 charac- terized in that said sleeve further comprises a heat reflector at said interior wall thereof, for reflecting heat produced by said heat source back toward said heat source, to aid in maintaining combustion thereof.

The smoking article of claim 9 charac- terized in that said sleeve is of a paper-type material. active element 11 and an expansion chamber tube 12, -18-

11. The smoking article of claim 10 charac- terized in that said paper-type material is spiral wound paper.

12. The smoking article of claim 11 charac- terized in that said paper is porous.

13. The smoking article of claim 11 charac- terized in that said paper is non-porous and is per- forated.

14. The smoking article of claim 9 charac- terized in that said heat reflector is a sheet of aluminum lining said interior wall. ooo8

15. The smoking article of claim 14 charac- ooooo Sterized in that said sheet of aluminum is perforated. 0 6 0

16. The smoking article of claim 15 charac- 0o0 terized in that said sleeve has a permeability of 0 4 about 9.1 to about 15.1, said aluminum sheet having at least about 4% open area. 0040 o

17. The smoking article of claim 9 charac- 0t terized in that said sleeve has a permeability of about 9.1 to about 15.1. a c 00

18. The smoking article of claim 2 charac- terized in that said sleeve comprises a substantially air-impermeable inner sleeve within said sleeve adjacent 0 00 said flavor bed.

19. The smoking article of claim 18 charac- terized in that said inner sleeve comprises a lip for receiving said heat source. tobacco filler or an inert substrate on which desira- ble compounds have been deposited.

In a preferred -19- The smoking article of claim 13 charac- terized in that said inner sleeve is a laminate of a metalsi~c foil and paper.

21. The smoking article of claim 20 charac- terized in that said inner sleeve comprises two metallic foil layers surrounding a paper layer.

22. The smoking article of claim 21 charac- terized in that said metallic foil is aluminum foil.

23. The smoking article of claim 2 further .haracterized by a perforated end cap at said distal end of said element, for preventing dropout from said element of said heat source and ash from the e 5 combustion thereof. a all

24. The smoking article of claim 23 charac- a 00 0 0 terized in that said end cap is reflective of radiant 00 QG0 0 0 energTy for reflecting heat back to said heat source, to aid in maintaining combustion thereof.

The smoking article of claim 1 further 0 characterized by a mouthpiece element adjacent said 11 IVmouth-end. 4 4

26. The smoking article of claim 25 charac- terized in that said mouthpiece element comprises a cellulose acetate filter plug adjacent said mouth end.

27. The smoking article of claim 26 charac- terized in that said mouthpiece element further comprises a rod of tobacco filler adjacent an end of said filter plug remote from said mouth end. Turning to the details of the construction of article 10, active element 11 is housed in a comr- l ni;i i

28. The smoking article of claim 1 charac- terized ii, that said heat source is solid, ignitable and self-sustaining.

29 The smoking article of claim 1 charac- terized in that said heat source is substantially cylindrical.

The smoking article of claim 1 charac- terized in that said fluid passage is substantially through the center of said heat source.

31. The smoking article of claim 1 charac- terized in that said heat source comprises carbon. te e

~32. The smoking article of claim 31 charac- Sterized in that said heat source comprises carbon 5 and at least one burn additive. t t

33. The smoking article of claim 1 charac- terized in that said flavor bed comprises tobacco.

34. The smoking article of claim 33 charac- 1 terized in that said flavor bed comprises a plurality of tobacco-containing pellets. s

35. The smoking article of claim 1 further characterized by means for cooling said aerosol.

36. The smoking article of claim 35 charac- S" t terized in that said cooling means comprises means for causing expansion of said aerosol.

37. The smoking article of claim 36 charac- terized in that said cooling means comprises an orifice at said second end of said active element, for passage therethrough of said aerosol, and an expansion chamber of the saturated vapors to form a stable aerosol, thereby minimizing condensation on either of mouth- 1 B a -21- adjacent said orifice toward said mouth end of said smoking article.

38. The smoking article of claim 1 further

39. The smoking article of claim 38 charac- terized in that said spacer means comprises a metallic clip.

The smoking article of claim 39 charac- terized in that said metallic clip comprises aluminum. 9

41. The smoking article of claim 38 charac- terized in that said spacer means is blackened, whereby said spacer means absorbs heat from said heat source and radiates heat to said flavor bed.

42. A smoking article substantially as hereinbefore described with reference to the accompanying drawings. D A T E D this 21st day of July, 1989. PHILIP MORRIS PRODUCTS INC. By its Patent Attorneys: CALLINANS t C A/mkn ril sbtnilya hreibefre escibd wth efeenc tot/